Alfred anthony



(No Model.)

A. ANTHONY.

VARIABLE THROW CRANK.

No. 584,809. Patented June 22,1897.

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SPECIFICATION forming part of Letters Patent No. 584,809, dated June 22, 1897. Application filed November 23, 1896. Serial No. 613,230. (No model.) Patenteclin England October 14, 1896, No- 22,829.

To all whom it may concern.-

Be it known that I, ALFRED ANTHONY, a subject of the Queen of Great Britain, residing at Oolchester, in the county of Essex, England, have invented a new and useful Improvement in Variable-Throw Cranks, (for which I have obtained Letters Patent in Great Britain, No. 22,829, hearing date the 14th day of October, 1896,) of which the following is a full and clear specification.

This invention relates to an improved variable throw crank which is particularly adapted for use in velocipedes, motor-cars, and the like; and it consists, essentially, of a crank-arm, to the outer end of which is connected, by means of a ball-bearing, a short swinging link, the free end of which is adapted to carry the pedal or its equivalent, the movement of the said link being controlled by a spring so arranged and adapted to operate that when the swinging link is forced to the extreme limit of its movement it becomes automatically locked in that position by the said spring, the object being to automatically produce an elongation of the crank during that portion of the stroke at which power is applied for propulsion in a manner more perfect than at present obtains.

I am aware that many attempts have been made already to construct a variable-throw crank, but those of which I am aware have failed from theoretical as well as practical reasons.

To obtain the best results, it is essential, first, that the crank shall commence to extend at the earliest possible point after passin g the upper verticalposition; secondly, that the extension shall take place. graduall y and smoothly and not suddenly with a jerk;-

thirdly, that the swinging link be so guided with respect to the crank-arm that the strain caused by the overhanging pedal shall not twist or distort the swinging link; fourthly, that the length of the swinging link be as short as possible and the bearing by which it is attached to the crank-arm be of maximum size, so that the whole of the strain 011 the pedal shall be carried by the said bearing without any other guide; fifthly, that the construction shall be such as will cause the greatest possible amount of the power applied to the crank to be transmitted to the latter through the pivot of the swinging link and the least possible amount thereof through the spring controlling it, thus avoiding overstraining of the spring and enabling a lighter spring to be usec.

In the accompanying dra\vings,whicl1illustrate this invention, Figure l is a view in side elevation of one form the invention may assume. Fig. 2 is a similar view of a modification thereof; and Fig. 3 is a view in crosssection on line a: 00, Fig. 1.

Throughout the views similar parts are marked with like letters of reference.

The crank-arm A is provided with the usual eye a at one end, adapted to receive the axle to which it is attached by a transverse cotter-pin in the manner well known.

On the other end of the crank-arm is formed a disk (1, having curved recesses adapted to form parts of two races of a double ball-bearing by which a swinging arm B is pivoted to the crank-arm A, the other parts of the said races being formed by a disk 1), formed on the swinging arm B and on the head 0 of the pivot O, respectively, as shown, the said pin being adapted to screw into the disk b for the .purpose of adjustment and being provided with a lock-nut c for looking it. The free end of the swinging arm B is provided with an eye I) to receive the pedal-pin. This eye may be of the construction shown or of any other suitable construction.

To the periphery of the disk I) is pivoted arod D, adapted to slide in a cylinder D, pivoted to a snug or projection a on the crank-arm A. Part of the rod D is threaded to adapt it to carry a collar 01, adapted to slide in the cylinder D. Onto the open end of the cylinder D is screwed a cap D provided with a suitable hole for the passage of the rod D. On the rod D are mounted two springs E and E, the one (the stronger) being located Within the cylinder D between its closed end and the collar 01, and the other between the collar 61 and the cap D The spring E is adapted to act between the crank-arm A and the swinging arm B'to return the latter to its normal position after it has swung out to increase the effective leverage of the crank, and the spring E acts as a cushion to prevent the too sudden return of the arm B. To prevent undue strain on the spring connection, a stop, such as N, is formed on the disk 1), adapted to come into contact with the arm A. By arranging the point at which the cylinder D is pivoted to the crank-arm A, as shown by Fig. 1, and dispensing with the stop b the spring E will act, as shown in dotted lines, as a lock to retain the swinging arm 13 in its extreme position for elongating the crank-arm until it is released by jerking the pedal with the foot.

The swinging arm 13 may be arranged either below the crank-arm A, as shown by Fig. 1, or above it, as shown by Fig. 2, but I find from experiment that the former gives the best results in practice.

Although I prefer to pivot the swinging arm B to the arm A by means of a disk double ball-bearing, as shown, I do not limit myself to the use of such a pivot-bearing, as a double cone-bearing Will fulfil the conditions.

I am aware that prior to the date of myin- Vention cranks have been fitted with swinging or extending arms, and I do not, therefore, claim such broadly; but

What I do claim, and desire to secure by Letters Patent, is-

In a variable-throw crank,the combination, with a crank-arm, and an arm B for carrying the pedal journaled in the free end portion of the said crank-arm; of a cylinder pivoted at its bottom end to the crank-arm, a cap at the top of the said cylinder, a rod pivotally connected to the arm B and slidable in the said cap, a collar secured to the said rod and slidable in the said cylinder, a spring E arranged between the said collar and cap, anda spring E stronger than the spring E and arranged between the said collar and the bottom of the cylinder, substantially as set forth.

ALFRED ANTHONY.

WVitnesses:

A. G. MUMFORD, H. WYATT. 

